1. Field of the Invention
The present invention relates to an image processing device, an image processing method, and a program for providing an image with no blur from a plurality of images acquired by a camera array image capturing device.
2. Description of the Related Art
Accompanying an increase in the number of pixels and improvement of the zoom function of a recent image capturing device, a blur of a captured image caused by a camera shake when capturing an image becomes a technical issue and an image capturing device with a camera shake correction function is used widely. As a system to realize such a camera shake correction function, there is generally known an optical camera shake correction system that optically corrects a camera shake by a gyro sensor that detects an angular speed caused by the camera shake and a drive unit that controls the relative position of a lens and an image capturing element so as to eliminate the camera shake.
As a different system, there has been proposed an electronic camera shake correction system that generates an image with no blur by taking in a plurality of images at a high shutter speed and by electronically aligning and superimposing the plurality of taken-in images (for example, Japanese Patent Laid-Open No. 2006-074693). This electronic camera shake correction system does not need any gyro sensor, and therefore, has an advantage not only in downsizing the image capturing device but also in suppressing the manufacturing cost.
As another method for acquiring a captured image in which the influence of a camera shake is suppressed, there is a method for continuously capturing images (bracket capturing) with different shutter speeds (for example, Japanese Patent Laid-Open No. 2009-239822). In this method, a camera shake is detected when the shutter is half-pressed and when the amount of shake is not more than a specified value, one image is captured as usual but when the amount of shake is not less than the specified value, bracket capturing is performed. This method has an advantage in that it is made easy to capture an image with no blur by performing bracket capturing.
However, in the electronic camera shake correction system proposed in Japanese Patent Laid-Open No. 2006-074693, it is premised that each acquired image includes no blur, and therefore, when a blur is included, there is such a problem that it is not possible to successfully perform image alignment between each image. Further, when capturing an image of a night scene etc., noise tends to be applied to the captured image, and therefore, an exposure time of a fixed period of time or more is necessary to reduce the noise. If the exposure time is lengthened, it is more likely that a blur is included accordingly and image alignment between each image becomes insufficient. As a result of that, the electronic camera shake correction system described in Patent Document 1 has such a problem that it is not possible to sufficiently correct a camera shake even by adding and combining images after the image alignment.
On the other hand, in the bracket capturing proposed in Japanese Patent Laid-Open No. 2009-239822, the image capturing time is lengthened, and therefore, there is a case where preferred shutter timing is missed when there exits a moving subject in the scene to be captured. Further, when there is a difference between the amount of shake at the time of half-pressing of the shutter and that at the time of actual image capturing, there is a possibility that even one image with no blur cannot be captured because it is not possible to perform bracket capturing with a preferred combination of shutter speeds.